Should full crowns be a last choice when considering reconstruction of anterior teeth today, rather than a first choice? In Figure 1, we see a catastrophic failure of a ceramic crown done using a “conservative” crown preparation design. Magne and Belser1 have demonstrated the extreme tensile stresses present in the palatal cemento-enamel junction (CEJ) area in a virgin incisor when the tooth is loaded. Any axial reduction in the palatal CEJ area is crippling to the maxillary tooth because the already high stresses naturally present in this area are greatly multiplied. This is a problem even when the axial reduction is minimal; ie, 0.5 mm. Throughout time, with constant masticatory function, stress corrosion occurs in the palatal dentin until eventually the crown can suddenly snap off at the gumline. This results in an irretrievable failure in most cases with the need for a subsequent extraction. Ask yourself, how would you feel if your central incisor snapped off today at lunch?
THE DIRECT BIOCLEAR360° COMPOSITE VENEER/CROWN
The Bioclear Matrix System was introduced in 2007. A Diastema Closure Matrix process patent and a Restoratively Driven Papilla Regeneration patent were granted by the US patent office in 2013. The Injection Molding Process patent was granted in 2015 by the US patent office to overmold teeth with a balance of heated flowable and heated (regular) paste composite.
|Figure 1. A catastrophic snap-off failure just 8 years after what appears to be a conservative axial reduction prep had been cut. (Image courtesy Dr. Jihyon Kim, Mercer Island, Wash.)||Figure 2. Bioclear 360° veneer matrix. Currently sold as a 6-tooth kit (12 matrices), the notched gingival portion allows deeper seating and is comfortable to the patient.|
|Figure 3. Before and after images of a now-happy patient.||Figure 4. Monolithic Overmolded Composite restorations contrasted with the before image of “patchwork” composites.|
The original Bioclear Matrix is remarkably strong in spite of only being 50 μm thick. This gauge of mylar (which is the same as old-fashioned, flat mylar strips) is popular for anterior composites such as Class III restorations, closing diastemas, treating undersized and peg laterals, and eliminating the “dreaded black triangle” present in 30% of adults and probably 75% of post-ortho adult cases. The many shapes and sizes allow for a wide variety of applications. The ultrathin width of these matrices allow for a tight contact without using wedges in many cases.
The next generation of the Bioclear Matrix is significantly stiffer. The Bioclear Veneering Matrix is 75 μm and is as strong as stainless steel (Figure 2). It comes in kit with a paired 2-part (mesial and distal) matrix that snaps around anterior teeth to allow easier reconstruction of teeth when no diastemas or large black triangles are present. It comes in a 12-piece, canine-to-canine kit. The anatomic shape allows the matrix to seat easily into the sulcus without bleeding. Interproximal scallops account for the presence of the papilla (patent pending). Heated composite is injected into the forms once the tooth has been prepared. Preparation of the tooth involves blasting off biofilm, lightly sanding the contacts with True Contact sanders, and removing any decay and/or old restorative material. There are several unique advantages to both the patient and the clinician (Table 1).
A female patient presented for her new patient examination recently. She was referred by her daughter, Sarah, who is an excellent hygienist in our office. The patient was on a limited budget and requested that 2 of her old and yellowing composite resin fillings be replaced. After reviewing her photographs with her, at the consultation appointment, I suggested that replacing old fillings alone was not going to make a significant impact on her overall smile (Figures 3 to 5). Instead, I recommended 5 Bioclear360° veneer restorations. It should be noted that orthodontics and porcelain reconstruction were also discussed with the patient, but she declined those more extensive, expensive, and invasive options.
The first step of the procedure was to determine if any prominent areas of the teeth would need to be sacrificed to be able to create uniform coverage with composite resin. In this patient’s case, the mesial of the right lateral needed to be reduced (Figures 6 and 7). I generally use shade B1 body Filtek Supreme Ultra (3M) for most cases, which can be seen in Figure 8 being tried in and light cured on the tooth for patient approval. Next the teeth were disclosed (Bioclear dual-color disclosing agent) and then blasted carefully to remove biofilm (Bioclear Blaster). Minor bleeding often occurs during this procedure, and this can be easily controlled with the use of Astringedent (Ultradent Products). Old restorations were removed and all sharp areas were rounded. Long bevels are also helpful. Incisal edges can be predictably restored if certain guidelines are followed. (The reader is encouraged to read part 1 of this article series [Dentistry Today, January 2016], which outlines the requirements to predictably restore incisal edges with composite resin.)
|Figure 5. Retracted preoperative view demonstrating multiple aesthetic problems.||Figure 6. Oblique view shows the rotated lateral incisor that needed to be reduced on the mesial aspect. (Note: This was the only area that required aggressive reduction.)|
|Figure 7. Occlusal photograph reveals that we had ample space on the central incisors to add enough thickness of composite resin to successfully hide the dark color of the teeth without amputating tooth structure.||Figure 8. Filtek Supreme Ultra (3M) (shade B1 body) was placed on the tooth for patient shade approval. Remember to keep the teeth wet during this time to avoid color confusion. Also, make certain the composite is light cured before showing the patient, as most composites get brighter after curing.|
|Figure 9. The old restoration has been removed from just the one incisor. This allows me to not lose the landmarks and have trouble later with symmetry and midlines.||Figure 10. The set of Bioclear360° Veneer matrices were seated and trimmed.|
|Figure 11. The 37% phosphoric acid was injected into the forms and was well controlled during etching and rinsing.||Figure 12. Incisal view of the completed injection shows a palatal and facial “umbilical cord” (intentional composite resin excess) that was left undisturbed until after light curing.|
Next, the teeth were restored one at a time to achieve tighter contacts (Figures 9 to 14). Intentional excess was left at the injection zones, while the critical interproximal and sugingival areas needed little to no finishing. Each tooth had a gross shape, but final shaping was done with coarse discs (Sof-Lex ET [3M]). Finally, the 3-step polishing technique was done to achieve a mirror finish that rivaled porcelain for brilliance. (A brief narrated video of the procedure is posted on YouTube, the Bioclear Matrix website or at the Dentistry Today website. It is titled “Bioclear360° Veneer.” Details of the 3-step “rock star” polish are also in this video [Table 2]).
HEATING OF COMPOSITE AS A FOUNDATIONAL ISSUE
When I first began injection molding of composite, I suffered needlessly with cold composite resin. It adapts poorly to the tooth, distorts the matrix, and leads to overhangs and huge voids. Nearly everyone utilizing the Bioclear Method who has made the move to warming the composite resin (Bioclear HeatSync) raves about the benefits realized by doing this additional step (Figure 15). Simply put, to make composite resin as predictable as porcelain, heating is a must.
|Figure 13. Facial view of the intentional excess.||Figure 14. Once the right central had a rough shape, the left central incisor was disassembled and restored.|
|Figure 15. The Bioclear HeatSync unit. This warming unit creates ideal thermal liquefaction of composite heated to 155°F.||Figure 16. Postoperative view reveals an ideal smile architecture as the smile-line follows the shape of the lower lip.|
|Figure 17. Postoperative oblique view.||Figure 18. Retracted postoperative view with the ideal combination of pink and white: healthy pink tissue, minimal amputation of tooth structure, and ideal shapes that eliminate black triangles.|
Heated composite has been around for a long time now, nearly 20 years. Until we started injecting composites recently, there was no real urgency to use heating. Now it is a must. Composite is safe to the pulp and soft tissue because composite acts like a thermal insulator. It has low specific heat, like popcorn. It can be very hot, but it doesn’t burn you. On the other hand, metals have high specific heat. That is why any heating of metal instruments that are to be used in the mouth is to be avoided.
WHAT IS THE SCIENCE BEHIND THE BIOCLEAR METHOD?
There was recent research showing that the Bioclear Method was significantly faster than the Mylar Pull Technique and resulted in 100% of the samples with an ideal contact, versus only 80% with the Teflon technique.2 Additionally, there are multiple studies demonstrating that composite can be heated for extended periods without any negative affects to the composite.
Final views of the case show the mixed porcelain and Bioclear360° Veneers smile. A common sight: the composite teeth have tissue that is healthier, pinker, and prettier than tissue near the porcelain margins3 (Figures 16 to 18).
- Mange P, Belser U. Bonded Porcelain Restorations in the Anterior Dentition: A Biomimetic Approach. First Ed. Chicago, IL: Quintessence Publishing Co.; 2002: 28-36.
- Kwon SR, Oyoyo U, Li Y. Influence of application techniques on contact formation and voids in anterior resin composite restorations. Oper Dent. 2014;39:213-220.
- Clark DJ, Kim J. Optimizing gingival esthetics: a microscopic perspective. Oral Health. 2006;96:116-126.
Dr. Clark maintains a private practice in Tacoma, Wash, and is the founder of the Academy of Microscope Enhanced Dentistry. He is also a course director at the Newport Coast Oral Facial Institute and the director of the Bioclear Learning Center in Tacoma. He is on the editorial board for several journals and has lectured internationally. He served for 18 months as the lecturer for CRA (now CR Foundation) and served on CRA’s board of directors for many years. His main areas of interest include the redesigning of restorative and endodontic access preparations. He can be reached at email@example.com.
Disclosure: Dr. Clark is the owner of Bioclear Matrix Systems.